Add rotation ability to material editor preview.

[AnilBK]

Mesh editor(Inspector while selecting MeshInstance3D) already had the ability to rotate the preview of currently edited mesh.

That feature is added to material editor.Just a copy paste from mesh_editor class.

Normal Preview:

normal-preview.mp4

Shader Preview:

shader-preview.mp4

Useful especially while shader editor is zoomed. If more primitives are added along with the built in sphere and cube then, it low key would act like that scrapped dedicated shader editor PR.

[akien-mga]

Code looks good to me, I'll let @JFonS or @aaronfranke confirm feature-wise.

[JFonS]

The feature looks good. I think this needs a rebase and some code clean-up as @aaronfranke mentioned.

[AnilBK]

The feature looks good. I think this needs a rebase and some code clean-up as @aaronfranke mentioned.

I still coudn't figure out how to implement code clean-ups as @aaronfranke mentioned.
So, I don't know what to do further.

This PR is still good as it is, since it's the same way mesh editor's preview code implements.

godot/editor/plugins/mesh_editor_plugin.cpp

Lines 69 to 74 in cca072a

	void MeshEditor::_update_rotation() {
	Transform3D t;
	t.basis.rotate(Vector3(0, 1, 0), -rot_y);
	t.basis.rotate(Vector3(1, 0, 0), -rot_x);
	rotation->set_transform(t);
	}

[fire]

Can I ask for a rebase? Want to review it again for godot 4 beta

[AnilBK]

Can I ask for a rebase? Want to review it again for godot 4 beta

Rebased.

[aaronfranke]

Sorry about my comment of "Just do it like this" earlier, I just checked and actually the rotation order is different for this code, so trying to do it that way won't work as expected.

[fire]

Test does what I expected.

[akien-mga]

Thanks!

[timothyqiu]

Cherry-picked for 3.6.